Dissolved Oxygen and Primary Productivity Lab

I. Abstract
This focus of this lab is to test the effect of different factors on the oxygen levels of an aquatic environment. In the lab the effects of temperature on oxygen levels and light intensity on primary producers in an aquatic environment were tested. The results and observations of this lab nearly perfectly followed the expected trends. The coldest water had the highest level of oxygen and the algae that received the most light produced the most oxygen. The results of the lab concluded that oxygen is able to dissolve better in colder water, as well as that light intensity on a fresh water ecosystem allows primary producers to produce higher levels on oxygen through photosynthesis

II. Introduction
Oxygen is critical for all life on Earth. Oxygen is equally important for fresh water biomes as it is for terrestrial ones. The level of dissolved oxygen in an aquatic environment is dependent on a number of factors, and can distinguish the water quality of the habitat. One of the most important of these factors is natural light. The oxygen saturation in an aquatic environment depends on the ability of plants to photosynthesize, which produces oxygen as well as organic molecules; therefore the more light that is able to reach the plants under the surface of the water, the higher the level of dissolved oxygen in the environment will be. The other source of oxygen in aquatic environments is through diffusion with the air. This process depends on factors such as temperature of the water and the amount of pressure of oxygen in the air. Therefore environments with high light exposure and low temperature will have much higher level of dissolved oxygen. Finally, dissolved oxygen levels in aquatic environments are influenced by the amount of pollutants in the water. Pollutants increase the level of nitrogen and phosphorus in water. These nutrients allow microbial organisms such as plankton and algae, which consume high levels of oxygen in the water. These microorganisms also will sink to the bottom of the environment at night, dragging oxygen within the environment with them.

The primary purpose of this lab is to observe dissolved oxygen levels in fresh water environments under exposure to various influential factors. This lab will study two primary questions; How does temperature affect the amount of dissolved oxygen in water? How does light intensity affect primary producers? During this lab, the effect of temperature and light intensity in a fresh water environment will be studied through measuring the level of oxygen in various samples. The first test will involve measuring temperature through the fixing and titration of controlled fresh water environments at three temperatures. The second test involves exposing various samples of algae-containing aquatic environments to different light intensities over a 24 hour period. In theory, this will allow the algae to photosynthesize better in environments that are exposed to more light, therefore these samples should have higher levels of dissolved oxygen. For example, a pond that is covered by a large oak tree will have a much lower oxygen level to one that is exposed to direct sunlight. In this lab, oxygen levels will be tested in cyanobacteria. This bacteria is a type of algae that will allow us to test how algae effects oxygen levels in water.
I hypothesize that if a cool fresh water environment is compared to a warm one, then the oxygen saturation will be higher in the colder one. I also hypothesize that if fresh water environments are exposed to various light levels, then the level of oxygen saturation will increase as the level of light exposure increases.

IV. Discussion
I accept my hypothesis that the oxygen level would be higher in the colder water, because the tests observed in the lab displayed that the coldest water was the most saturated with oxygen. I also accept my